Float control switch



Jan. 3, 1939. s o j 2,142,680

FLOAT CONTROL SWITCH Filed July 12, 1937 2 Sheets-Sheet l W I I123 a .227 .l.

Jan. 3, 1939. J H 2,142,680

FLOAT CONTROL SWI TCH Filed July 12, 1937 2 Sheets-Sheet 2 Jufzzz LShrade Patented Jan. 3, 1939 UNITED STATES FLOAT CONTROL swrrcn John L.Shrode, Richmond Heights, Mo., assignor to Alco Valve Company, Inc., St.Louis, Mo.

Application July 12, 1937, Serial No. 153,253

5 Claims.

This invention relates to electrical circuit make and break mechanism ingeneral; and more particularly to mechanism of this character operablein response to variations in level of a liquid in any 5 vessel tocontrol the supply of liquid thereto.

The main object of the invention is to provide a float controlled switchof the explosion-proof type adapted for use in hazardous atmospheres,such as are encountered in oil' level control during the refiningprocesses, whereby the level of highly volatile products, such asalcohol, ether, and refrigerant liquids, may be controlled withoutdanger of ignition caused by sparks which would ordinarily result by theoperation of switches having electrical conducting surfaces exposed tothe explosive atmosphere.

Other objects of the invention will become apparent as the detaileddescription thereof proceeds.

In the drawings:

Figure 1 is a central vertical section through one form of theinvention;

Figure 2 is a horizontal section taken on the line 22 of Figure 1;

Figure 3 is a central vertical section to a modified form of theinvention; and

Figure 4 is a horizontal section taken on the line 44 of Figure 3.

Referring now to Figures 1 and 2 of the drawings, the inventioncomprises a cylindrical body 5 closed at its lower end by a bottom plate6, having an internally screwthreaded liquid connection 1 formedthereon. A body plate 8 suitably secured to the body 5 near the upperend thereof, forms with said body 5 and bottom plate 6, a pressurechamber 9. the body plate and bottom plate being suitably secured to thecylindrical body 5 as by Welding or otherwise. A gas connection isprovided in the body near the upper end of the chamber 9, the said gasconnection l0 and liquid connection 7 serving to connect the pressurechamber 9 in parallel with any vessel designed to have its liquid levelcontrolled in accordance with the level of liquid in the said pressure45 chamber.

The body plate 8 is provided at its center with an aperture H in whichis suitably secured the lower end of a non-magnetic tube I2, the upperend of which serves as a support for the top l3 of the relay housing l4.The relay housing I4 is cylindrical and of substantially the samediameter as that of the cylindrical body 5. The lower end of the housingis laterally offset to form an annular flange l5 adapted to fit snuglyover the upper end of the body 5.

The shoulder formed in the lower edge of the housing l4 by the annularflange I5 is provided with an annular recess IS in which is seated therelay housing gasket ll of rubber, or other suitable resilient material.The upper end of the tube i2 is closed by a plug l8 having an externallyscrewthreaded shank l9 projecting axially through an aperture 20 formedin the center of the top l3 of the relay housing. A nut 2| engages theshank l9 to clamp the housing l4 securely against the gasket l7, andthereby form an effective airtight casing for the electriccircuitclosing mechanism above referred to.

The relay or switch mechanism is mounted on and surrounds thenon-magnetic tube 12. This mechanism comprises a permanent magnet 22having the arms 23 and 24 thereof apertured to fit snugly over the tubel2. The magnet 22 is supported in vertical position on the tube l2 bymeans of a fiber tube 25, the bottom of which rests upon the body plate8, and the upper end of. which contacts with and supports the lower arm24 of the magnet 22. A short section 26 of fiber tube extends betweenthe upper arm 23 of the magnet and the lower surface of the top ii ofthe housing l4, to clamp the magnet 22 securely in position on thenon-magnetic tube II.

A float 21 is arranged within the pressure chamber 9, and has a rod 28extending from its upper end axially into the tube l2. A plunger 29 ofmagnetic material is secured to the upper end of the rod 28. Thenon-magnetic tube l2 completely encloses the plunger 29 and the rodconnecting it to the float. 21, and is of sufficient length to permitthe necessary axial movement of the plunger in response to liquid levelchange as imposed upon the float 21 by change in level of the liquid inthe pressure chamber 9.

An armature 30 for the magnet 22 is pivoted at its lower end to the arm24 of the magnet. A pair of tension springs 3i and 32 are secured at oneof their ends to the magnet arm 24 and at their other ends are securedto 2. lug 33 projecting from the lower end of the said armature.Normally these tension springs would hold the armature in the dottedline position shown in Figure 1, with its upper end separated from theupper arm 23 of the magnet. However, the tension of these springs ispredetermined so that the attraction of the magnet for the armature willhold it in the full line position shown in the drawings to provide aclosed magnetic circuit for the lines of force of the magnet.

When the float supported plunger 29 is raised to a position within thetube [2 in which it comto the lower part of the armature fill andhaving,

a contact terminal 35 fixed to its outer end adapted to make contactwith a cooperating terminal 35 fixed to a bracket 3'? insulated from andsuitably secured to the relay housing 96. Suitable wires ti and 38connect the respective tenals 35 and 3b to any apparatus designed to becontrolled thereby. A conduit connection as is secured to the upper endof the body 5 above the body plate 8 to serve as a passageway for suchwiring as may be necessary to connect the relay to the said apparatus.

The modified form of the invention illustrated in Figures 3 and 4 issubstantially the same as that shown in Figures 1 and 2. In this form,however, an electrical induction coil in and a magnetic fr'ame dl aresubstituted for the permanent magnet 2'2, shown in Figure 1, the coil itbeing retained in place between the arm or pole pieces t2 and 63 bymeans of a screw dd pass ing freely through an aperture in the polepiece 42 and screwthreaded into an internally screwthreaded aperture inthe lower pole piece 53. The armature and other operating partsconnected thereto are substantially the same as the corresponding partsshown in Figure l and are identi-' fled by the same reference numerals.

when low temperatures are encountered, such as commonly occur inrefrigerated vessels, it is desirable to isolate the relay mechanism soas'to permit insulation of the pressure chamber 9, in order that violentebullition created by high rates of heat absorption will not cause falseliquid levels within the float chamber. It is also desirable to effectthis isolation and insulation in order to prevent freezing of themercury within the mercury switches, when switches of this character areused within the relay housing.

The insulation above referred to comprises a block of cork t5, centrallyapertured to receive the non-magnetic tube as secured at its lower endto the body plate d. The tube 38 is substantially the same asthe tube52, shown in Figure 1 of the drawings, and is similarly secured at its Iupper end to the relay housing it, which in every respect is the'same asthat shown in Figure 1. The tube it must, of course, be correspondinglylengthened to compensate for the length of the insulation insert 65. Thelower end of the relay enclosing chamber is formed by a cylindricalcontainer fill, the bottom of which is centrally apertured to receivethe tube (it, and is provided with an upstanding annular boss or flangeis serving as a seat for the lower end of the tube 25', which forms asupport for the magnetic frame ll. The other elements of this form ofthe invention are the same as are shown in Figure 1 of the drawings andare identified by the se reference numerals.

While the switches shown in the drawings are of the common springcontact type, it must be understood that the invention is not to beconsidered as limited to any particular kind of switchaisao anon-magnetic tube extending through the pole pieces thereof, an armaturepivoted to the end of one of said pole pieces to swing toward and fromthe other pole piece and normally held by said magnet in position toclose the magnetic circuit therethrough, means for swinging saidarmature away from said other pole piece when the flux through themagnet is shunted from said armature, aplunger of magnetic materialslidable in said tube to bridge said pole pieces, and a I circuit makerand breaker connected to said armature ior operation by the movementsthereof.

2. Liquid level-controlled electric switch mechanism, comprising acasing, a partition dividing the casing into a liquid-containing chamberand a relay housing, a horse shoe magnet mounted in said housing, anon-magnetic tube extending from said chamber through said partition andthe pole pieces of said magnet, an armature pivoted to one of said polepieces to swing toward and from the other pole piece and normally heldby said magnet in position to close the magnetic circuit therethrough,means for swinging the armature from said circuit-closing position whenthe flux through the magnet is shunted from said armature, a floatwithin said chamber, a plunger connected to said float and slidable. insaid tube from the other pole piece and normally held by said magnet inposition to close the magnetic circuit thereth, means for swinging thearmature from said circuit-closing position when the flux through themagnet is shunted fromsaid armature, a float within said chamber, aplunger connected to said float and slidable in said tube transverselyof said pole pieces to shunt said armature, and a circuit er and breakerconnected to said armature for operation by the swinging movementsthereof, said partition and tube forming an hermetic seal between saidchamber and the circuit-closing mechanism in the relay housing.

4. Liquid level-controlled switch mecha comprising: a -21 a partitiondividing the casing into a liquid container and a relay housing, a tubeof non-magnetic material extending,

2,142,eao

in said tube.

5. A switch comprising a horse shoe magnet. an

armature pivoted at one 5 pieces of said magnet to the other pole piecean end to one 01' the pole swing toward and from d normally held by saidmagnet in position to close the magnetic circuit across said polepieces, means for swinging the armature away from said other pole piece,and

circuit make and break mechanism operably controlled by the swinging ofsaid armature.

- JOHN L. SHRODE.

